In the manufacturing process of information processing equipments for controlling hard disk devices and other related devices, it is customary to conduct a voltage marginal check as a part of quality assurance testing procedure. In the voltage marginal check, marginal check voltage which is obtained by varying feedback voltage from the power-supply device or the reference voltage upward and downward within a certain range is used to check if logical circuits or memories of semiconductor devices are in proper working condition.
Japanese published and unexamined patent application gazette H11-352195 refers to exercising voltage marginal check for the information processing equipment that has no provision of interface for voltage marginal check, by inserting a voltage marginal check power-supply device between the power-supply device and the logical board or device.
Japanese published and unexamined patent application gazette H5-232197 refers to a voltage regulator circuit, which, built-in in an integrated circuit, can perform marginal check of source voltage. Also, Japanese published and unexamined patent application gazette H7-280889 refers to a voltage marginal test method, according to which turning on a test switch enables the test program to operate and vary the output source voltage to upper limit, lower limit and specified values.
[Patent Document 1] Japanese published and unexamined patent application gazette H11-352195
[Patent Document 2] Japanese published and unexamined patent application gazette H5-232197
[Patent Document 3] Japanese published and unexamined patent application gazette H7-280889